The energy consumption of ...

The energy consumption of the aerated system can be lowered significantly by using Delta Hybrid blowers from Aerzen. Fine bubble plate diffusers will also reduce the energy consumption. I've seen this happen at Dutch water authorities. Also remember that modern pumps and things like soft starters have a significant lower energy consumption than stuff from the 80's. The Dutch water authorities have a major focus on energy reduction the last years. This to lower the carbon footprint and to lower the operational costs. You can ask them for independent advice, they are willing to share their knowledge with countries outside Europe. 

Then some not so independent advice; The BIOPAQ®UBOX from Paques is a combination of anaerobic and aerobic waste water treatment build on top of eachother. Due to the anaerobic part, the energy consumption is much lower than in a fully aerated system. We have very good experiences with these system on communal waste water in Brazil. Paques has a sales office and a brand new factory in the south of India. So that could be a good option for your case.

 http://en.paques.nl/products/featured/biopaq/biopaqubox